In vivo administration of granulocyte colony-stimulating factor increases the surface expression of sialyl-Lewis(X) on neutrophils in healthy volunteers

We examined the in vivo effect of granulocyte colony-stimulating factor (G- CSF) on the surface expression of putative counterligands for endothelial s electins on neutrophils in healthy volunteers. G-CSF (50 mu g/m(2)/day) was administered subcutaneously to 5 healthy volunteers for 4 days. The expres sion of surface antigens on neutrophils was determined by flow cytometry an d monoclonal antibodies. G-CSF administration increased the number of leuko cytes, mainly of neutrophils, which was associated with an increase in the expression of the high-affinity Fc receptor for IgG (FcRI, CD64) and CD 14 on neutrophils. G-CSF administration decreased the surface expression of Lr selectin on neutrophils, whereas it increased the expression of sialyl-Lew is(x) but not Lewis(x) on neutrophils. These findings suggest that G-CSF pa rticipates in the neutrophil-endothelial cell interactions in vivo by modul ating the expression of adhesion molecules and ligands for endothelial sele ctins on neutrophils.